Process of making potassium sulfate, &amp;c.



c. A. DOREMUS. PROCESS ORMAKINGPOTASSIUM SULFATE, 6w. 'APPLIOATIONKFILBD APB-11.3, 1912.

1 ,054 ,5 1,8 Patented Feb. 25; 1913.

Residue Trem wifh ATTORNEYJI BEST AVAILABLE COP onrrnn saaras rara s r OFFICE.

CHARLES A. DOREMUS, OF NEW YORK, N. Y., ASSIGNOR OF ONE-HALF TO JOHN SHERMAN I-IOYT, OF DARIEN, CONNECTICUT.

PROCESS OF MAKING POTASSIUM SULFATE, 8w.

To all whom it may concern Be it known that 1, CHARLES A. Donmnfs, a citizen of the United States, and a resident of New York, county of New York, and State of New York, have invented certain new and useful Improvements in Processes of Making Potassium Sulfate, &c., of

which the following is a specification.

the feldspars and a general commercial. method for obtaining both potash and a use-. ful alummum compound from refractory feldspathic materials. v

The drawing is a diagram illustrating difi'erent s aps of my improved process.

It has been suggested that feldspar maybe decomposed by l'iydrofiuosilicic acid to obtain the separate silicofiuorids of potassium and aluminum. Although feldspar is very common and found in large quantities in this country, so far as l am a\ "are no process has been successfully and commercially carried out to obtain the valuable and much desired potassium sulfate (K SOQ, so valuable for fertilizers. There are probably several reasons why the hydrofiuosilicic acid method has not been used.

In the best form of my improved process I treat finely powdered orthoclasc or the double silicate of potassium and aluminum (K Q il O GSiO with aqueous hydrofluoric acid in the proportions of 20 parts by weight of the powdercdpotash feldspar to 129 parts of the aqueous hydrofluoric acid containing 20% of real acid at a temperature of about 50 (1., stirring the mixture thoroughlv. The proportions will of course vary with different fcldspars or silicates used according to the percentages of different metals present. The mixture becomes further heated by .the chemical actions which take place and there results in a short time a complete decomposition of the Specification of Letters Patent.

Application filed April 13, 1912.

'silicotluorid Patented Feb. 25, 1913, Serial No. 690,591.

feldspar. I then cool the mass somewhat and filter out the insoluble potassium silicotluorid, leaving the aluminium compound in solution. The aluminium compound may be treated in any suitable manner to obtain other useful aluminium compounds; for instance, it may be treated with sulfuric acid in a known manner to produce aluminium sulfate, and the silicon tetrafiuorid, hydrofluoric acid, etc, may be treated to recover hydrofluoric-acid to be again used in the first step of the process.

According to one form of my invention the potassium silicotluorid may be treated in any known manner to obtain a useful potassium compound or compounds as by the known treatment with sulfuric acid, whereby potassium sulfate is obtained, and the fluorin may be suitably recovered by any known method to be again used in the'first step. This method, however, has many disadvantages. When the K SiF, is heated with tin excess of the concentrated sulfuric acid, hydrotiuosilicic acid is driven off more or less decomposed and some acid potassium sulfate is prdduced, and this must be heated to produce the neutral or normal sulfate. I therefore prefer to treat the potassium according to my improved method which not only avoids these disadvantages but has several distinct advantages, including cheapening the production in several ways. To do this according to the best form of my method, I take the dry potassium'silicoiiuorid and intimately mix therewith finely powdered. calcium sulfate, preferably anhydrous, and preferably in molecular proportions. If gypsum be used I use 220.5 lbs. of potassium s ilicofiuorid and 172.19 lbs. of the finely ground gypsum. I next heat this mixture in a suitable retort or mutlle. I have found that heating to incipient red heat yields good results. The mass is left in a form easy to leach. The escaping gases. principally silicon tetrafiuorid (Siifl) are conducted to appropriate condensing apparatus and the fluoriu may be recovered as hydrotluosilicic or hydrofluoric acid. to be again used in the first step of the process. according to the form of the invention employed. The residue which consists of a soft friable mass then lixiviated with hot water. The potassium sulfate dissolves in the water and is easily secured in crystalline form by known the potash bearing mic-as may JES I AVAILABLE con- .acts similarly and magnesium sulfate, preferably anhydrous, may also be used to react wlth the silicofluorid of the alkali metal reproduce the sulfate of said metal. All these I include in the term sulfates of the alkaline earth metals, and any one or more of them may be used with success, although the calcium sulfate is preferred. Other reagents may also be found which react with the silicofluorid to produce a soluble salt of the alkali metal or metals, and an insoluble fluorid.

WVhile I prefer orthoclasc feldspar (K,O,Al,O,6SiO, l as a base, and while the use of this distinct silicate has many advantages over other silicates, nevertheless-other refractory silicates such as microcline and be used. Other silicates including those of sodium, may also be used as a base, and se 'iarated, and may then be treated according to the improved second step of my process in order to obtain soluble sodium compounds, etc. Moreover, while the use of aqueous hydrofluoric acid has distinct advantages in the first step of the process since it acts almost instantaneously, causing a complete reaction quickly and because it requires no heat and leaves the insoluble silicoliuorid of the metal or meta -s of the alkalissubstantially pure and free from silica, nevertheless other fiourin acids such as hydrofluosilicic, when followed by my improvrd method of treating the silicofluorid, may be used with some success, as thereby certain of the disadvantages are removed.

My process has a further distinct advantage in that besides obtaining the potassium sulfate in a cheap manner from the common feldspar, at the same time, I obtain byproducts, including ccrtain useful and valuable aluminum compounds.

Although I have described my improvements with respect to certain embodiments with great detail, nevertheless I do not dos sire to be limited to such details except as clearly specified in the appended claims, since nnmy changes and modifications may well he made without departing' from the spirit and scope of my inrr-ntion. in its broader aspects.

Ilaving fully and clearly described my improi .lllGJllS, what I claim as new and dc- .sirc to secure by l dlllll'h' Patent, is:

l. The improved process of making poluw slum sulfatr, which comprises heating potassium silico'tluorid with calcium sulfate and disolving out the potassium sulfate.

The improved process of making potassium sulfate, which comprises treating potassium silicofluorid with a sulfate of one or more of the alkaline earth metals.

3. The improved method of producing sulfates of the alkali metals, which comprises treating a silicofiuorid of an alkali metal with a sulfate of one or more ofthe alkaline earth metals to produce a sulfate of the alkali metal.

4. The improved method of making sub fates of the alkali metals, which comprises heating substantially to incipient red heat, a silicofluoiid of an alkali metal with a sulfate of one or more of the alkaline earth metals.

5. The improved method of making sulfates of the alkali metals, which comprises heating a silicofluorid of an alkali metal with a sulfate of one or more of the alkaline earth metals in the proportion of their molecular weights.

6. The production of a sulfate of an al kali metal by heating the silicoiluorid of the alkali metal with an anhydrous sulfate of an alkaline earth metal, substantially as described.

7. The improved method of producing sulfates of the alkali metals, which comprises trcating a silicolluorid of an alkali metal with a sulfate of one or more of the alkaline earth metals to produce a sulfate of the alk: li metal, then separating the soluble sulfate of the alkali metal from the insoluble iluorid of the alkaline earth metal by means of a suitable sol vent, substantially as described.

8. The production of potassium sulfate by heating potassium silicolluorid with a sulfate of an alkaline earth metal, in the proportion of their molecular weights, toincipient rcd heat, lixir'iating the resulting mass with water, separating the soluble potassium sulfate from the insoluble calcium .iiuorid and crystallizing the fate, substantially as described.

9. The improvedmethod of obtaining useful cmnpounds from refractory feldspars, which consists 'Hl treating the refractory feldspar with, aqueous hydrofluoric acid, separating the insoluble potassium Dual AVAILABLE CUP suitable reagent to obtain a useful potassium compound.

11. The improved method of treating refractory silicates containing one or more alkali metals and one or more other metals, which consists in treating the silicate with aqueous hydrofluoric acid to produce an insoluble compound of the alkali metal or metals and a soluble compound of the other metal or metals, and then separating the soluble compound or compounds from the insoluble compound or compounds to obtain useful products thereof.

12. The improved method of producing useful compounds from refractory silicates of potassium and aluminium, which consists in treating the silicate with a fiuorin acid, separating the insoluble potassium silicofluorid and the soluble aluminium compound, and treating the potassium silicofluorid with a sulfate of a metal of the alkaline earths, and separating out the resulting potassium sulfate.

13. The improved method of making useful compounds from refractory silicates, which consists in treating the refractory silicate with aqueous hydrofluoric acid, separating the insoluble from the soluble constituents produced thereby and treating the insoluble constituent with a sulfate of an alkaline earth metal.

14. The improved method of obtaining useful compounds from refractory silicates, which consists in treating the refractory silicate with a tiuorin acid, to produce an insoluble silicofluorid of a metal of the alkalis and a soluble compound, then treating the insoluble silicofluorid with a sulfate of an alkaline earth metalto produce a sulfate of the alkali metal.

.5. The improved method of obtaining useful compounds from orthoclase, which ('HIISlStS in treating the feldspar with aqueous hydrofluoric acid, separating the insolu-' lilo potassium silicofluorid and the soluble aluminilun compound, and heating the potassium silicofluorid with a sulfate of an alkaline earth metal" to obtain potassium sulfate.

16. The improved method of making potassium sulfate from orthoclase, which consists in treating the orthoclase with aqueous hydrofluoric acid in substantially the proportion of 20 parts powdered potash feldspar to 129 parts of aqueous hydrofluoric acid containing 20% real acid, separating out the insoluble potassium silicofluorid and treating said potassium silicofluorid with a reagent to obtain potassium sulfate.

17. The impro'zed method of making potassium sulfate from orthoclase, which consists in treating the orthoclase with aqueous hydrofluoric acid in substantially the proportion of 20 parts powdered potash feldspar to 129 parts of aqueous hydrofluoric acid containing 20% real acid, separating out the insoluble potassium silicofiuorid and treating said potassium silicofluorid dry with a sulfate of an alkaline earth metal to obtain potassium sulfate.

18. The improved method of making soluble salts of the alkali metals, which consists in heating to incipient red heat a silicofluorid of the alkali metal with a reagent to produce a soluble salt of the alkali metals and an insoluble fluorid.

19. The improved method of producing useful compounds from refractory silicates of potassium and aluminium, which consists in treating the silicate with a fiuorin acid, separating the insoluble potassium silicofiuorid and lhesoluble aluminium compound, and treating the potassium silicol'luorid with a salt of an alkaline earth metal to produce a soluble potassium salt and an insoluble fluoricl.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

CHARLES A. DOREMUS.

lVitnesses GORIIAM Caesar, llnwrx SEC-ER. 

